Probabilistic-risk-assessment applications in the nuclear-power industry

Abstract

There has been a remarkable growth in the use of probabilistic risk assessment (PRA) methods in the US nuclear industry, both commercial and government. Use of PRA techniques has been expanded appreciably in the 1980s and 1990s as a result of the Individual Plant Examination (IPE) process. The IPE program calls for all existing nuclear utilities to use PRA methods to seek out plant vulnerabilities, and for all new applications for commercial nuclear power licenses to include full-scope PRA for design certification under 10CFR part 52. Effort must be spent to improve the consistency of PRA models, applications, evaluation approaches and processes among the nuclear utility industry. Standards are needed to guarantee proper application of PRA methods in risk-based regulation (RBR) in order to establish and maintain consistency in PRA applications. One standard application method that fits every aspect of RBR is difficult if not impossible. However, some of the PRA tasks or processes can be effectively standardized, e.g., level of detail, bounding limits on the failure rates of human recovery actions, and ways and means of data analysis. This paper discusses some historical background about the application of the PRA and identifies: appropriate efforts that the industry can spend to standardize the PRA applications in RBR; improvements in PRA techniques to achieve standardization; the benefits utilities would gain as a result of this harmony; and some of the limitations in areas which stubbornly resists standardization.